Just a Little IF Padding

My 902 MHz transverter board is stuffed and ready to check out. But first, I need an appropriate IF signal.

I have a 2 meter HT that can be dialed down to 20 mW (13 dBm) on its lowest power setting. That's within spittin' distance of the 0 dBm that I need. So I built an attenuator pad that's adjustable from 10-13 dB of attenuation. Perfect!

It seems like I'm awfully close to getting some 902 MHz RF out of my first homebrewed transverter. Maybe tomorrow.......

1152 MHz LO Working

Okay, today I finished stuffing the 1152 MHz LO board, which goes with the W1GHZ 1296 MHz "Right Side Up" transverter. Since I hit a few landmines with the 756 MHz board, I double-checked a few things before applying power. All looked good, so on she goes.......

And yes, it's working right out of the chute. As you can see from the photo, I'm only getting -8.58 dBm out of this LO, although my test cable which is about 10 feet long is soaking up about 1 dB.

Paul Wade (W1GHZ) says he got -5 dBm out of his prototype, but that some trimming of the R2 and R3 bias resistors on the last two stages of amplification may be necessary for maximum power output. I'm 2.5 dBm off, but I guess we'll see just how much is really needed when it comes time to connect this to the transverter board, which has another stage of amplification for the LO input.

Next task is to get a 144 MHz IF rig to drive this stuff with. The trick is that these transverters only want to see about 1 mW of drive, so it's going to take some finagling to get the output of any of my rigs down to that level. I'll let you know what I figure out.

73 de W9HQ

Okay, now it works.....

Alright, that's better. As I said in my last post, the output of the 756 MHz LO board for my 902 MHz transverter (W1GHZ design) was only putting out -28 dBm, so something was obviously wrong. Now, to find out what it was.

Worst case was that I had blown all the MMICs when I accidentally hooked the power up backwards for a split second. (Did I really do that? Uh, well, yeah, I did.) Time to find out. So I pulled C4 and put a test probe on there and sure enough I had 0.5 dBm at 252 MHz out of the first filter stage. So at least I knew that A1 right after the crystal oscillator was working. Phew! Dodged that bullet.

I wasn't too keen on actually slicing the board to test right after the second amplifier stage, so instead I double checked the values of the bias resistors. They were okay. Could it be that running the bias to A2 through a leaded ferrite bead changed the resistance of that path enough to matter? Unlikely, but I removed the ferrite. Same deal.

So I decided to re-flow the solder connections to A2 and A3 and, in doing so, noticed that I had the bias resistor to A3 going to its ground pin, not its output, one via over. Ah ha! Moved that over and....Bingo! 6.68 dBm of beautiful RF at 756 MHz.

Next up......the 1152 MHz LO board for the 1296 transverter.

It Lives! .....but it limps....

In a group buy sponsored by W8ISS, I bought the PCBs and parts for LO/transverter boards to build W1GHZ transverters for 902, 1296, 2403, and 3456 MHZ. I have stuffed the LO and transverter boards for 902 and 1296 MHz, but had no way to check them out. I was recently able to borrow a spectrum analyzer for a few weeks, so now I'm scrambling to get as many of these boards up as I can. I've just applied power to the first piece in the line-up, the 756 MHz LO board for the 902 MHz transverter. It's definitely oscillating at 756 MHZ, but unfortunately the signal is at about -28 dBm. The docs for the W1GHZ design say I should be seeing about +5 dBm. Well, I guess that's why they call it troubleshooting. Still, this is extremely cool. I never thought I would be into VHF-UHF-SHF operating, let alone building my own gear for these freqs!

Paul Wade, W1GHZ, has done the amateur community a real service in these simple transverter designs. If you have to buy all the parts outright, you can expect to pay about $70-80 per band which is still darn cheap. But if you can get in on a group buy, that price will drop to sub-$50, which is really incredible. What a fantastic way to experiment with SHF. I have already learned a ton of good stuff and I'm sure both learning and fun have just begun.

73 de W9HQ

January 2010 VHF-UHF Sweepstakes

Okay, time to update this blog more often. My problem—both in blogdom and in other parts of my life—is that I let the best become the enemy of the good. In this case, I always want photos and details all lined up so that the blog posting is as complete and interesting as possible. But then I never quite get around to blogging at all. Enough of that.

My son Christopher (KC9JTL) and I had a great time in the January 2010 ARRL VHF-UHF sweepstakes. One really cool aspect of this contest was hearing so many locals on the air, on both FM and SSB.

As for locals on FM we worked KB9TPG, KC9LBO, K9ALT, KC9OYG, KC9NHQ, KC9KVJ, W9ET, KC9MRV, WX9EP, and N9UNW.

Local contacts on SSB came from WV9E, WV9S, KA9FOX, W9UUM, W9GM, W9RPM, N9ETD, KB9BGN, and AB9HW. (I hope I'm not forgetting anybody.)

I think that's just great, so thanks again for everybody who got on the air!

Christopher and I made a total of 93 contacts. Here's the breakdown:

Freq QSOs Grids

50 27 9

144 52 14

222 9 6

440 5 1


That's almost twice as many contacts as we got last January, which was our first VHF-UHF contest. And conditions were pretty poor this weekend. Hope to do better in June.

W9HQ operates BY4DX from Shanghai

Late last year, during my annual trip to China, I had the privilege to operate the amateur radio club station BY4DX.

China does not have a reciprocal operating agreement with the U.S., so you have to get special permission to operate there and can only do so at a club station. During my first trip to China, the license didn't come through from Beijing in time. And during the second trip, I was just too busy!

This time, though, my work colleagues helped me get in touch with the members of the BY4DX club and so I met them on Saturday morning, October 17, 2009 for a trek outside of Shanghai to their temporary club station. They were getting ready for the inaugaural kick-off of the club station the next day, but they were kind enough to let me have an early crack at operating the station.

I was happy to hear that this was only a temporary location for them. Unfortunately (and they had told me about this ahead of time) there was a huge amount of RFI across the spectrum. The noise was S9 on all of 20 meters, making it very difficult to operate. I began calling CQ on that band and did make a few contacts, but soon stopped because I could tell that there were people calling me whom I just could not hear. Didn't seem quite fair to them. So I tuned around the band listening for really loud stations and called them instead.

Finally I switched to 15 meters, where the noise level was only S6 or so. There I called CQ and, after a while, got on the other end of an honest to goodness pile-up. The band was open to the west and so most of the stations calling me were from Russia, the Ukraine, etc.

During my afternoon at BY4DX I was able to contact Guam, Japan, Taiwan, Hong Kong, several provinces in China, Russia, Ukraine, Muldova, and Austria. Pretty cool. Hopefully, by the time I return, they will have moved into their permanent location in Shanghai itself and the conditions will be better.

These are great guys and I had a great time.

KC9JTL-R in the ARRL 2009 September VHF Sweepstakes

Christopher (KC9JTL) and I had a great time roving to the EN42-52-43-53 grid convergence by Dodgeville, WI for this contest. We got a bit of a late start, but the beautiful drive down there was shorter than I expected, so we arrived more or less as planned, but initial set-up took a bit longer than planned so we got on the air from EN42 about 5:15 pm on Saturday evening.

Our antenna lash-up was as follows. I have a hitch carrier for the back of the Suburban, so we built a platform to which we bolted a roof tripod for a mast. Thanks to a donation by KC9IWE we had a push-up mast mounted on the tripod. On that I put a 6 element WA5VJB "cheap yagi" for 222 MHz, then a 4 element beam for 2 meters, then a 10 element beam for 432 Mhz. On top of it all I put a rotatable dipole for 6 meters that Christopher and I made out of an old fiberglass puptent pole covered with aluminum foil. Rotation was via an "armstrong" rotor.

Our plan was to try and get some 2 meter FM activity going—we even brought a separate 3 element beam for vertically polarized work on 2 meters—but unfortunately FM was a bust. We CQed all the way down and beamed back toward the north but never heard a peep (except N9WU/R who was already down at the grid convergence and heard us right off.)

When we set up on an old airport runway just outside of Dodgeville, we found right off that the feedline was hosed on 432. So we had to settle for QRP FM into a handheld "cheap yagi" from EN42 until we could replace the feedline when we stopped in EN52. And the other glitch is that we found that my FT-897D was almost totally deaf on 6 meters—we had at least half a dozen guys tell us that they could hear us just fine, but we could either not hear them at all or just barely. Still trying to figure out whether that's a hardware problem or some software setting. So we left some 50 MHz Qs on the table.

The really pleasant surprise was 222, on which we had just 1.5 watts from a Yaesu VX-6R into a 6 element WA5VJB "cheap yagi" (I now have an Elecraft XV-222 transverter on that band, thanks for KC9BQA, but I didn't have time to build the needed interface with the FT-897). As you can see below, we made as many Qs on 222 as we did on 432 with 20 watts into a 10 element yagi. So that's a very inexpensive way to get a real footprint on that band.

The whole antenna set-up worked out pretty well. We even moved the vehicle with everything up and in place to transition from EN52 to EN53 (granted, it was only about 1/4 mile on a back-country road).

Despite the inevitable obstacles and limited operating time, we made 75 QSOs. Headed back home much too late, but Christopher kept me awake by filling me in on all sorts of arcane Bionicle lore. It was a lot of fun and we'll definitely be doing it again.

QSOs Multipliers
50 10 10
144 39 26
222 13 13
432 13 13